As is known, a coke oven gas-collecting system includes an ascension pipe, leading from a coking chamber, which is connected through an elbow to the gas main for the coke oven installation. A nozzle projects through the wall of the elbow and is used not only during operation of the ovens for the introduction of an ammonia-containing liquid at a pressure of several bars, but is also used to extract, with the use of very high pressure liquid, the gases evolved during charging which pass upwardly through the top gas-collecting chamber and the ascension pipe into the main. It is, of course, desirable to provide a nozzle which will produce a spray having the maximum possible effect in extracting undesirable components from the evolved gases.